Improvement in electroplating with alloys of gold



UNITED STATES PATENT OFFICE.

A. BERTHOUD, OF NEW YORK, N. Y.

IMPROVEMENT IN ELECTROPLATING WITH ALLOYS OF GOLD.

To all whom it may concern:

Be it known that I, ACHILLE BERTHOUD, of No. 214 William street, in the city of N ew York, State of New York, have invented certain Improvements in Gildin g Metals; and I do hereby declare the following to be a full and exact description thereof.

The nature of my invention consists in a preparation or process or means by which I am enabled to deposit a compound metal of gold and copper, or gold and silver, or gold, copper, and silver upon a metallic surface to resemble an alloy of gold of any desired color or fineness and of any required thickness.

The proportions of materials I employ are best in the following quantities, but may be varied therefrom: one hundred and fifty parts ferrocyanide of potassium or sodium, seventyfive parts phosphate of soda, fifty parts carbonate of soda or potash, twenty five parts neutral sulphate of soda.

First, dissolve the above in eight quarts of rain-water and add the ammonia precipitate resulting from four pennyweights of chloride of gold, wash well, boil twenty minutes, and, when cold, filtrate, which constitutes the goldbath second, dissolve the nitrate of silver made from twenty pennyweights of silver and precipitate by chloride of sodium, wash the precipitate well to remove all the acid, and add to it the same solution as for the gold, but using it more concentrated, using but two qilarts of water, boil twenty minutes, cool, and n ter.

The special nature of my invention consists in the preparation of the copper solution, which is composed of a double ferro'cyanide of copper and potassium or sodium.

I dissolve nitrate of copper (or any salt of copper, preferring, however, the nitrate) resulting from twenty pennyweights pure copper, precipitate by ferrocyanide of potassium in proper quantity to precipitate all the copper, boil a short time, filter, and wash the precipitate. Boil this precipitate in the same salt as for the gold and silver, employing but two or three quarts of water, and, when cool, bottle it and put aside for use.

,To obtain any desirable color for the coat- *"ing, add or measure more or less of the two solutions of silver or copper to the gold-bath, according to the tint required. By closely observing the effect but a short time will be necessary to become skillful and familiar with the process and treatment.

A great advantage of this process consists in my being able to dispense with the use of cyanide or mercury or the galvanic battery, the employment of which are expensive, deleterious to health, and uncleanly, besides being of difficult manipulation, while my process is cheap, prompt, and sure, and the surfaces of the articles coated are preserved with all their finish perfect, however thick the coating may be. No burnishing or touching up is required, while the facility of the manipulation and the regularity of the process are such that the operator requires no previous chemical knowledge, which constitutes for this branch of industry a great stride in importance and usefulness. It is distinct and greatly superior to and gives results different from those obtained by the employment of baths allied to those of cyanogen, which demand a strong electric force and a knowledge of hydroplastic manipulations, and which present no regularity in the execution of the delicate work of gilding jewelry.

The solutions described do not oppose electrio currents.

I use an apparatus similar to that in ordinary use in the electrotype process for coating with copper, which consists in a porous cell filled with the gilding liquid, and within which the article to be coated is placed, con-' nected with a cylinder of zinc surrounding the porous cell, the whole being placed in a vessel of iron or other proper material, filled, however, with a strong solution of chloride of sodium instead of acid. This apparatus and contents I heat while in use to about 60 or 80 centigrade.

I do not claim the use of solutions ot'ferrocyanide of cop perin cyanide of potassium, such having already been used in the electrotype process; but

I claim as my improvement in electroplating metals- 1. The employment of the solution of copper prepared substantially in the manner as above set forth.

2. The employment of solutions of gold and silver, prepared substantially as above set forth, in admixture with the described solutions of copper.

3. The abovedescribed process of electroplatingmetals with alloys of gold so as to produce any desired color.

A. BERTHOUD.

"Witnesses:

J. B. HYDE, S. BERTHOUD. 

